Electrical storage of intelligence



April 12, 1960 E, p, G, wR|GHT ETAL 2,932,688

ELECTRICAL STORAGE OF' INTELLIGENCE 7 Sheets-Sheet 1 Filed June l, 1954 Atto neya' April 12, 1960 E, p. G, wRlGHT ETAL 2,932,688

ELECTRICAL sToRACE CE INTELLIGENCE Filed June 1, 1954 Y 7 sheets-sheet z Pakt-Hb@ 7' t f2 4 626 4 25 4' 624 4 C23 4 '2E GM 6/6 6/2 a @/0 l as f5-/ 3 Y @/7 /5 C WM 3 G 0 2 3 4 5 W f2l c/7 5 M IX, G54 c2 C26 "L 23624 c25 ff5'/ "'5'0 Inventors 6.9 G wRlGHT- Lancs J. D. REYNOLDS Harney ELECTRICAL STORAGE OF INTELLIGENCE E P. G. WRIGHT-J. RICE' J, D. REY NOLDS April 12, 1960 E- P G, wmGHT ETAL 2,932,688

ELECTRICAL STORAGE OF' INTELLIGENCE Filed June 1, 1954 7 Sheets-Sheet 4 F/ .6. 4- 02-3 C24 c25 y S 7K7/ 70 Lin@ M L.. n venters ,E E G.WRIGHTJ. RICE' J. D. REYNOLDS Byz a; S.

A itam e y April 12, 1960 E, p. G, wRlGH-r ETAL 2,932,688

' ELECTRICAL STORAGE OF INTELLIGENCE' Filed June 1, 1954 7- Sheets-Sheet 5 CH/ CH2 CH3 f w r 2. 7h1e Sra/e opera/es for 2nd character and reap/:es stap element.

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Inventors E. P. G.WRGHTJ.R ICE' J. DREYNOLDS Werf A Morne y April 12, 1960 Filed June l,

E. P. G. WRIGHT ETAL 2,932,688

ELECTRICAL STORAGE OF INTELLIGENCE 1954 7 Sheets-Sheet `6 KK is operai/ed F-l 7' SMSMS MSMSM SSMSS T SMSMS MSMSM SSMSS .Nextjnb fw f l F74 f l F94 rM/sMs/ns MsMsM ssMsL TMISMSMS MSMSM SSMSS TM/sMsMs MSMSM ssMss /st c/ldmcfer tmnsmitted and 75l @fiery/'sed TMISMSMSMZMSMSM SSMSS Wave/bpms dur/'ng Transmission Inventor-s E. P. G. WRIGHT- J.RICE- J. o. Rev NoLos A tlorn ey Aprll 12, 1960 E, p. G, WR|GHT ETAL 2,932,688

ELECTRICAL STORAGE OF INTELLIGENCE Filed June l, 1954 7 Sheets-Sheet 7 /0- Saseyuent cyc/e$(wit/| TSZ energfsed) FLJ L KR restored Hg. a Waveform: dur/'ng #msm/lesion.

Inventors E. P. G.WRIGHTJ.RICIE J. D.RE YNOLDS Wwf-47% Attorney iQeiCS f.

United TIhis invention relates to electrical systems for the storage of intelligence, with particular, though not exclusive reference, to the storage of constant total permutation code characters.

According to the invention there is provided equipment for the storage of intelligence which comprises a plurality oi' stores, means for receiving intelligence in, and/ or transmitting intelligence from, said stores, means for applying a distributor mark to a store as being the next to be used for reception or transmission, means for transferring such mark from store to store, means for detecting such mark, and means for directing information into or from a marked store under control of said detecting means.

in telegraph switching systems, and in certain industrial A.telecommunication systems, the necessity arises for storving teleprinter messages for periods of time, which may be long or short, and for retransmitting the messages with for without modiiications, land with or without a re- ;:arrangement of order.

Systems for effecting this are well known and comprise such devices as paper tape in which signals repre- ;senting incoming messages may be punched and magnetic tape in which the incoming signals may be stored by magnetic changes in the magnetic material of the tape.

A wide variety of storage devices is now coming into :use in which intelligence can be recorded by creating f'internal strains in the material of the store, and in which zstored intelligence or predetermined portions thereof can lbe detected by detecting the state of strain in the ma- ;terial or in corresponding portions thereof.

The invention is to be described with reference to a fparticular embodiment in which the form of temporary storage used is a magnetic drum or disc such as has been tused in electrical brains as a storage device. Such a -magnetic drum consists, for example, of a hollow brass drum having a magnetic skin on its cylindrical surface. 1T his skin provides a number of closely spaced peripheral tracks, with each of which there is associated a recording head and a reading head. Each track provides a number -of separate stores and the drum is mounted on a spindle frotatable at high speed by an electric motor.

Intelligence is recorded in the form of successive un- :spaced longitudinal magnetisations of either one or two kinds, which can conveniently be designated or zero, `and l or one. Hence it will be seen that intelligence is conveniently recorded in binary digital code, though other code forms are possible. When a recording is to be `altered this is done by recording on top of the former recording, i.e. by the magnetic recording technique known 4as overprinting Each track is divided into a number of separated lengths of track by magnetic markings or the like which leave no physical indication of the division on the actual track. The recording and reading heads are spaced from one another, so that the recorded intelligence is read off, and recorded in a different position, this being elected 'with such modiiication of the recording as is necessary. Systems of this type are described in our co-pending applications, Serial Nos. 289,383, 289,385 and 289,386, all led May 22, 1952.

Vpulse cycle, are used to control all operations.

"icc

Additional to the tracks on which intelligence is stored there is a track having a recording per element position of all storage tracks. Associated with `this track, known as the elements or clock track, there is a reading head known as the clock head from which there is riVed a pulse per element position. By means of delay circuits, this clock pulse cycle is used to derive a set of three time-spaced, narrow pulses per element pulse. These are known as the t1, t2, t3 pulses. AI further additional track has a recording at the first-element posin tion of each storage section. This track is `known as the marker track and has a marker reading head associated with it. This gives a pulse cycle which deiines the commencement of each of the storage sections. These two pulse cycles, the clock `pulse cycle and the marker Individual applications may require special pulse cycles which can, in general, be derived from these two.

The invention will be described with reference to the accompanying drawing illustrating the embodiment referred to. In the drawing:

Fig. l is a diagram to show the allocation of the elements used for making the recording and the relative positions of the pulses and waveforms used during the circuit operation.

Fig. 2 shows the time scale arrangement associated with the reception and retransmission of telegraph signals.

VFig 3 `shows the register used for the temporary storage of received characters and characters to be retransmitted from the store.

Fig. 4 shows the control arrangement for making the recording and also for reading out at a later stage.

Fig. 5 shows the unit used for making the necessary recording.

Fig. 6 shows the unit used to retransmit characters as read from. the memory into the register.

Fig; 7 shows illustrative waveforms for the reception of a three character message.

Figs. 8(1') and (ii) show illustrative waveforms for the transmission of the message received as in Fig. 7, and

Fig. 9 is a block diagram which indicates the association of the circuits of Figs. 2 through 6.

In Fig. l, (a) shows the section of the drum associated with a particular recording. This section is divided into a number of elements, the first of which, T, is used in connection with the retransmission of a stored message. The element T is "0 when a message is being received but is caused to become l when it is desired to retransmit the stored characters. Elements M1, M2, M3, etc. provide a distributor operation for both the reception and retransmission of the message. In the initial state MI is a l and M2, M3, etc. are 0. With Ml in the l state, the first received character is stored in the live elements following M1 and, as the character is stored, M1 becomes "0 and M2 becomes "l so that the second received character will be stored in the tive elements following M2. This action proceeds until eventually M1, M2, M3, etc. will all be 0 showing that the message is fully received. When element T is made "l to show that retransmission can commence, the irst character passes from the drum store and at the same time M1 is made 1. Similarly as the other characters are read out from the drum the respective Mn; are made l so that, when the complete message has been retransmitted, M1, M2, M3,

essential functioning of the equipment (only its detailed 3 arrangement). A similar remark applies to the convention used in this specification of "1 for a space telegraph element and for a mark element.

The elements l'-5 are associated with the 5 variable elements of a telegraph signal in standard -unit constant total permutation code, the first variable element being stored in l, the second in 2, etc. It should be noted that there is no necessity to provide storage for the start and stop elements as these can be added at the time of retransmission, as will be described.

The waveforms and pulses used in the circuit operation are as follows:

PT is a pulse which becomes positive for the duration of element T.

PL is a pulse which becomes positive for the duration of the-last element of a recording section.

PM is a pulse which becomes positive for each of the Mn elements.

WM is a waveform which becomes positive for the sections of the drum which are used to store the telegraph elements. It can be seen that WM is positive when both PT and PM are zero.

r1, t2 and t3 are the pulses previously mentioned, which occur for each element, Il coinciding with the beginning of an element and t2. and t3 being progressively delayed.

Not shown in Fig. 1 but used in the circuit arrangement, are -p pulses. These pulses are intended to occur at a rate of 1 in 2rnsecs., i.e. 500 cycles/sec. In the description to follow it' will be assumed that the rotation time or" the magneticdrum is 20 msecs., the time of a uniperiod of standard teleprinter code. Thus, by having a clock track arranged to give pulses in each revolution, thte necessary -p pulses may be provided. As will be seen, 'a time scale operating on a ratchet start principle utilises these pulses. If it is considered that the starting error using 500 cycles/sec. as the basic frequency is too great, the rate of these pulses could be increased accordingly by suitably modifying the clock track and adding further dividing stages in the time scale.

Before passing on to a detailed description ofthe circuit, some explanation of the circuit conventions used is desirable, together with some description of the usage of the component partsl of the circuit. A similar form of circuit conventions may be found in U.S. Patent No. 2,653,996.

The circuits are shown throughout in functional form, a convenient arrangement for description since the basic electronic elements used are wellknown, few in number and comparatively simple in operation, and readily joined together to give a composite circuit arrangement.

Electronic coincidence gates, well-known per se, are shown as circles with incoming controls shown as radial leads with arrow-heads touching the circle. The output is shown with a radial lead with the arrow-head pointing radially outwards. The number inside the circle indicates the total number of controls which must be energized for the gate to deliver an output; for instance, if there are four controls, and the number in the circle is 2, then the gate will deliver an output when any two of its controls are energised. Gates are indicated by the letter G followed by a reference letter.

A counter comprising a number of single-component stages each of which is capable of assuming one of two conditions, on or off, is shown as a series of rectangles Y drawn in linear array, e.g. C1 or C2, Fig. 2. The counters a suitable control applied to the non-energised position, and is indicated similarly by the letter F and a reference number; individual outputs being designated by a lower case f.

A pattern movement register Yis shown as a horizontal row of separated rectangles linked together, with an input or controlling gate at the left, outlets being shown from any one or more of the separate elements. Inputs to individual elements may also be indicated by arrows. The usual indication is by means of an R and a reference number, with a decimal number for the individual sections, and a lower case r for the individual outputs as controls. A small circle at one corner of the right-hand ele-ment denotes that the register is non-recycling.

The phase inverter, shown as X1 in Fig. 3, is used to give a positive output where none exists, and vice versa, and is described and claimed in U.S. Patent No. 2,688,695. This device is useful when a positive output from an element is required, whatever its state, as in R1, Fig. 3. Thus rl-S'l is a normally positive control, but r1-5'0 is normally zero, i.e. ineffective. By interposing the inverter, however, it becomes a positive control for zero, but zero for the normal output (r1-51).

Referring iirst to the layout diagram of Fig. 9, a track on a magnetic drum is divided into a plurality of sections for the storage of items of intelligence. Adjacent the track there are located a recording head and a reading head, the former being associated with a recording circuit (Fig. 5) and the latter with a control circuit (Fig. 4). In Fig. 9, the rectangles bear an indication of the pertinent ligure showing the respective detailed circuit, and also of the reference or references used in such detailed circuit ligure to indicate the primary control component or components, that is, the time scale, shift register, and flip-flops.

ln the recording operation, items of intelligence, such as character code signals from a teleprinter T/P, are received over an incoming channel, and under the control of the time scale circuit (Fig. 2) are recorded successively in the shift register (Fig. 3), from which under the control of the control circuit (Fig. 4) and recording circuit (Fig. 5) they are recorded on successive sections of theY drum track.

When the storage of a message is completed, the character codes are successively read off the drum track by the reading head and under the control of the control circuit (Fig. 4) and time scale circuit (Fig. 2) are successively recorded in the shift register (Fig. 3). The shift register (Fig. 3), in conjunction with the retransmitting circuit (Fig. 6) and time scale circuit (Fig. 2) controls the energization of a transmitting relay TR which, by the actuation of its contacts, sends appropriate mark and space signals to the outgoing line.

To pass now to the description of the usage of the component parts of the circuit, the time scale of Fig. 2 will first be described.

It is assumed that recording and retransmission do not occur simultaneously so making it possible to use a common time scale, and also a common register, for each telegraph terminal.

The time scale consists of two stages, C1 and C2, C1 stepping, when operated, at a rate of l step for each -p pulse applied through gate g2, i.e. 1 step in 2 msecs., and C2 stepping once for each complete rotation of C1, i.e. l step in 20 msecs. C2 is shown as a lil-position counter although the circuit arrangement makes use of 8 positions only; this is simply due to the fact that a 1iO-position multi-cathode tube would provide a suitable practical realisation. Any other arrangement using individual gas tubes would be suitable.

The outputs of C2 are associated with a teleprinter character as follows:

As will be. seen-later, the time scale is returnedV to its rest position either before 71/2 uniperiods have elapsed from the commencement of the start element during reception or at 71/2 uniperiods during retransmission, the latter time being in agreement with normal teleprinter practice in which 71/2 unit transmission is used.

The time scale is controlled by means of two startstop pairs, F1 and F2, F1 being used for receiving a message from a teleprinter and F2 when a stored message is being transmitted.

KRO, the read-off key, is associated with the teleprinter position. KRO is in its normal position whilst the operator is sending a message to store and is operated when the operator has completed the message and wants retransmission to take place. At the end of retransmission the operator restores the key and conditions become as for the initial state.

As stated above, since recording and retransmission do not occur simultaneously, it is possible to use a common register, R1, shown in Fig- 3. However, by the use of two time scales and two registers the system could be modified for simultaneous operation.

The register is a pattern movement register of the type described in U.S. Patent No. 2,649,502. Gates G9--G13 are used for inserting information into the register When signals are being received from the teleprinter (or incoming line). When the five variable elements of a character have been stored, the pattern set up in R1 is stepped by means of G14 and G15, and the output of RLS is applied to a drum store for each step. To provide positive information for both a l or a stored in R15, an inverter, Xi, is incorporated so that for a 1, R1.5.1 is positive and R150 is zero and for a 0, R1.5.1 is zero and R1.5.0 is positive. Thishas been referred to previously. For convenience, it has been assumed that for a space variable element R151 will be positive and for a mark variable element R150 will be positive.

G16 and G17 are used respectively during retransmission for passing information to the register from the memory store and for stepping the pattern after each element has been received. So that the same number of stepping pulses as information elements can be used, instead of having to provide one less by more complicated arrangements, a register R1 having 6 positions namely 0 5 has been adopted.

Passing now to the control circuit of Fig. 4, F3 is the bi-stable pair used for staticising, element by element, information taken from the drum by the reading device. The arrangement is such that F31 is energised for a l read from the memory and F31 is energised for a 0.

F4 is the bi-stable pair which is used to note that information is to be passed to the memory, F41 energised denoting that information may be passed. In the initial state F42 is energised but when the time scale passes to the stop uniperiods, during reception of a character, G18 opens causing F41 to be energised. G19 is used to return to the state with F42 energised.

F5 is the bi-stable pair which allows information stored in the register, R1, to pass to the appropriate character storage section of the memory store. This is accomplished by energising FSL!` via G20, when the correct distributor element, Mn, is encountered. G21 and G22 are used to reset to F52 energised when the end of the appropriate section is reached.

F6 is the bi-stable pair which is used to note when information has to be passed from the memory to the register, and is analogous to F4 used for reception. F61 is energised via G23 when transfer has to take place and F62 is re-energised by either G24, G26 or G27 according to the circumstances.

F7 is the oi-stable pair which allows information to pass from the memory to the register. F7.1 is energised via G28 when the correct distributor element, Mn, is

. encountered, and is analogous to F5.1 used for reception.

d G29 and G30 used, te re-eaersse FM. when the aP- propriate elements havepassed to the register.

-F8 is the bi-stable pair which notes that the read-oi key, KRO, has been restored to its normal condition. Thus F8 is instrumental in returning the store to its initial state in readiness for receiving further messages.

In the recording unit of Fig. 5, F9 is the bi-stable pair the output of which is associated with the recording device to permit the wanted recording to take place.

G32 and G33 are used in connection with element T of the recording section (vide Fig. 1).

G34-G39 are used in connection with elements M1, M2, M3, etc., the multiplicity of gates being necessary to provide the distributor requirements, previously described.

G4-G43 are used in connection with the recording of the Variable elements of the telegraph characters, G40 and G41 being used to recopy a character as read by F3 (Fig. 4), and G42 and G43 being used to insert a new character.

The outputs of F9 are such that when a space telegraph element is to be recorded, F9.1Vis energised to record a l and when a mark telegraph element is to be recorded, F92. is energised to record a"0.

In the retransmission circuit, Fig. 6, F10 is the bistable pair used 4to control a relay TR, which in its turn controls the retransmission of characters read from the drum into the register R1. The controlling gates G46 G53 are associated with time scale positions as indicated by the c inputs applied thereto so that a start element may be added before the ve variable elements and a stop element added at the end. 71/2 unit transmission is provided. The beginning of each uniperiod is determined by output from 01.2 which is applied to Gt and G49. A control from f2.1 is added in the case of G46 so that Fit) does not move to the space side during reception-no such control is needed on the mark side.

With this introduction, it is possible to pass to` the detailed description.

The detailed description of the circuit operation will be given in conjunction with Figs. 7 and S, which illusrate the essential changes for each stage of the reception and retransmission. For illustrative purposes, a message of 3 characters only has been used, the five variable elements of these characters being assumed to be:

(l) Space Mark Space Mark Space (SMSMS) (2) Mark Space Mark Space Mark (MSMSM) (3) Space Space Mark Space Space (SSMSS) in the initial state the following are in the energised condition:

F12, F22, C:1.1, (32.1, F42, F62, F7.2, F82 and F102. No section of R1 is energised.

The condition of F3 is dependent upon the condition of the record already on the drum, that is, M1 is a 1, T, M2, M3, etc., are O and the character storage sections will be in the condition left from the previous recording. How this `state is brought about will be understood from the condition reached at the end of the circuit operation to be described. Fig. 7(a) illustrates the initial condition of the track section.

The condition of F9 is dependent upon the condition of F3, for, in the initial state, G34, G35, G40, G41, G44 and G45 are the only gates (with the exception of G33) which may open and it can be seen that F9 will he set at time t2 according to the setting of F3 at that time.

When the operator sends the start signal preceding the rst character, the send line SL (Fig. 2) changes to space and in so doing energises f1.1. G1 is opened and the next -p pulse to arrive will open G2 and C1 will step under control of the -p pulses. When C1 reaches CLG, G3 is prepared and the next pulse steps not only C1 but also C2 which moves to position 62.2.y When C1 reaches c1.5 with C2 at c2.2, i.e. 30 msecs. from the beginning 7 Vofthe start element, a time coincident with the centre of ,the rst variable element, the condition of the send line is examined by G9 (Fig. 3). This element is assumed to be"` space and so G9 will open and r1.5 will be energised, and a positive condition will appear at r1.5.1.

Ata time given by c1.5, r2.3, i.e. 50 msecs. from the beginning of the start element, the line is again examined, this time by G10. Since the second variable element is assumed to be mark, G10 will remain closed and r1.4 will remain non-energised. The time scale C1, C2 continues to step and subsequent elements are examined by G11, G12 and G13 in turn. With the assumed :first character (SMSMS), the register R1 will be set with r1.5, r1.3 and r1.1 energised, r1.4 and r1.2 non-energised.

After 120 msecs. from the beginning of the start ele- I'nent, C2 will step to c2.7. Since C2 will remain in this position for 20 msecs. and the drum will make one revolution in this time, there will be one PT pulse (Fig. 1) which will appear during this interval. (Slight variations of the rotational speed will also change the rate of the -p pulses which step C1 and C2 and so there will always be a coincidence between 02.7 and PT). Thus G18 (Fig. 4) will open and f4.1 will be energised. The operation of f4.1 energises f1.2 (Fig. 2) closing gate G1 and the time scale C1, C2 is stopped. The changeover of F1 also causes a reset signal R to be applied to G4 and the time scale is restored to c1.1 and c2.1 energised. The operation is illustrated in 1, Fig. 7.

The PM pulse which follows the PT pulse will open G20 (Fig. 4) and f5.1 will be energised; since M1 is a 1, f3.1 will be energised at this time and f4.1 has been prepared by the PT pulse. The operation of f4.1 also closes G34G36 (Fig. 5) but opens G37 with the aid of the PM pulses (G38 and G39 remain closed due to the lack of other required controls), so that at time t2, G45 opens causing f9.2 to be energised and 0 will be recorded for M1. At time t3 in the PM pulse, G19 (Fig. 4) opens and f4.2 is re-energised.

When the waveform WM coincident with the iirst code section appears, both G40 and G41 (Fig. 5) are closed since f5.2 is no longer operative. However, G42 and G43 are partially prepared by WM and f5.1. At time t2 coincident with the lirst element in CH1 (Fig. 7), r1.5.1 (Fig. 3) will be positive so that G42. (Fig. 5) and G44 open and f9.1 will operate causing 1, i.e. a space, to be recorded for the first element. At time t3, G14 and G15 (Fig. 3) open and the pattern in R1 will be stepped one position to `the right so that now r1.5 will record the second variable element and, since this is a mark, r1.5.0 and not r1.5.1 is positive. Thus for the second element, read at time t2, G43 and G45 (Fig. 5) will open and f9.2 will be energised causing to be recorded. Again the pattern in R1 is stepped via G14 and G15; the process is repeated for the following variable elements so that F9 Will have recorded the original contents of R1. The last step causes the register to be cleared with no positions energised.

For the PM pulse coinciding with M2, f3.1 is not energised so that G34 (Fig. 5) will remain closed. G35 remains closed under control of f5.2 which is still nonenergised but G36 is opened by f4.2 and f5.1. At time t2, G44 opens, f9.1 is energised and a 1 is recorded `for the M2 element. At time t3 during this PM pulse, G21 and hence G22 (Fig. 4) will open and f5.2 will be re-energised. In consequence, the existing elements in CH2 (Fig. 7) on the drum track will be recorded as read by f3.1 using G40 and G41 (Fig. 5), although at this time this is of no consequence for these elements will have been left over from the previous recording. G35 causes M3 to be recorded as O and CH3 (Fig. 7) is reproduced by means of G40 and G41. The state of the recording is now as shown in Fig. 7(b). It should be understood that the transfer of the first character takes place in the stop period (i.e. 30 msecs.) and no further from the teleprinter into the register.

character will be passing from the teleprinter Tr/P to F1 at this time. n

TheY second character isvnow sent from the teleprinter and, as for the irst character, is' passed by means of the time scale intoV the register R1. Whilst this is taking place the recording of Fig. 7(b) will be read by F3 (Fig. 4) and re-recorded by F9 (Fig. 5) exactly as read. 4Again when the time scale reaches c2.7, denoting that 'the variable elements have been received, G18 opens with pulse PT and f4.1 (Fig. 4) is energised. Since M1 is now a 0, the rst PM pulse after this does not open G2G. However, M2 is now a 1, so that the PMpulse coinciding with MZ'opens G20 and f5.1 is energised. (See 2, Fig. 7.) This causes the contents of R1, i.e. MSMSM, to be recorded by F9 in the element positions in CH2. Also because f4.2 is not re-energised until time t3 of the PM pulse coinciding with M2, both M1 and M2 will be recorded as 0 by means of G37 (Fig. 5). Until time t3 of the PM pulse coinciding with M3, f5.1 remains energised so that a 1 is recorded for element M3 by means of G36. The elements in CH3y will be recorded by F9 as read by F3. The recording is now as shown in Fig. 7(c), and remains the same until the next and last character is transferred.

The last character is now passed as previously described Again when the stop' element is reached (see 3, Fig. 7) f4.1 is energised. The rst l coinciding with a PM pulse occurs for M3. The elements prior to M3 will be recorded as read by means of G37 (Fig. 5) for M1 and M2 and by means of G40 and G41 for CH1 and CH2. For M3,-f4.\1 Will be energised and, in consequence, M3 will be recorded as 0 by means of G37. Also the PM pulse opens G20 (Fig. 4) and causes f5.1 to be energised. At time i3 of the M3 element, G19 opens and f4.2 is re-energised. The fact that f5.1 is energised during the CH3 element positions causes the contents of R1 (Fig. 3), i.e. SSMSS, to be recorded by F9. Since there are no further Mn elements, a pulse PT coinciding with element T is used to reset F5 to the state with F52 energised. The recording is now as shown in Fig. 7(d) and for -further cycles of the drum, this record will be read by,F3 and re-recorded by F9.

The operator having completely recorded the message can now, or at any time later, operate key KRO to transmit the message stored. In consequence, since positive potential is removed from NX and applied to X the Iirst PT pulse to occur after the key operation (see 5, Fig. 8) no longer opens G33 (Fig. 5) but instead opens G32 and energises f9.1 causing a 1 to be recorded in element T position. The remainder of the recording is made as read as shown in Fig. 8(e). The object is now to transfer the contents of CH1 into R1 so that the rst character can be retransmitted. In the next cycle, when element T is read, f3.1 will be energised and G23 (Fig. 4) will open and cause f6.1 to be energised. (See 6, Fig. 8.) For the next PM pulse, i.e. coincident with M1, G34 and G35 will remain closed. Instead G38 is opened and f9.1 is energised causing a l to be recorded for M1. Also at time t2, PM, G28 (Fig. 4) is opened and f7.1 is energised and at time t3, PM, G24 is opened and f6.2 re-energised. When the WM waveform associated with CH1 appears, at time t2, because both f7.1 and f3.1 are energised for the rst element, G16 (Fig. 3) is opened and r1.1? is energised. At time t3 of the same element G17 and G15 open and, in consequence, the contents of R11) are passed to R11. For the second element f3.2 is energised so that G16 remains closed but G17 again opens `and causes the pattern so far set up in R1 to be moved one position to the right. Eventually the 5 elements of CH1 will have been read via G16 into R1 and stepped via G17 so that the elements will be recorded, in order of appearance, in R15-R11. Since the first character is SMSMS, r1.5, r1.3 and r1.1 will be energised but r1.4 and r1.2 will be non-energised. As shown in Ar1.5.0 to become positive.

under control of G17.

l vf6.1 is energised.

8(f) `theelexnents are recorded'as read, the-,only variation between (f) and (e) being in respect of'1M1 which `has now become 1.

When the lPM pulse coinciding with M2 appears G29 (Fig. 4) is opened at time t1 and f7.2 is re-energised. At the same time, G5 and G6 (Fig. 2) are opened, and f2.1 is energised. This opens G1, andrGZ allows -p pulses to pass and the time scale begins to step.

At 01.2, G46 opens since G47 is already open to C21, so that flitl is energised. Relay TR operates, and tr?.

chan es over to its s or s ace side and a start signal is sent to line.

At successive times C22., 62.3, 02.4, c25 and C26,

'G50 and G52 will both open, and one or other of G51 Vand G53 will be opened depending on the signal then coming from R15. For the first inteliigence element of the tirs-t character, which is space r1.5.1 is positive and therefore G51 opens, followed by G47, and G46 at c1.2. i101 continues to be energised, and space continues to be transmitted to line. At c1.7, G55 and G15 (both in Fig. 3) open (G54 being open to 02.2) and R1 will be stepped.' to the right causing R15 to become mark now, for the second element of the first character, and

opens, followed by G48, and G49 at CL2. F10 charges over to f10.2, and TR contacts return to normal, causing a mark to be sent.

Again at 01.7, G55 and G15 open to advance the register, so that R15 will contain the third element, a space, `of the rst character, r1.5.1 is energised, and TR returns to space at c1.2.

In similar manner, the remaining elements are transmitted to line by means of the appropriate gates, the

operationsof F10, the operations of TR, and the stepping of R1.

When 02.7 is reached, and at time c1.2, G48 and G49 (Fig. 6), open, f1.0.2 is energised and trl return to normal to send a final mar signal -to line, as the stop signal.

This persists till the time c1.7, c2.8, i.e. 150 msecs. from A, the commencement of the signal, when G7 (Fig. 2) opens, f

and f2.2 is re-energised, stopping the time scale and generating the reset pulse T. This pulse opens G4 and the time-scale is reset with positions c1.1, c2.1 energised.

As shown in 7, Fig. 8, Whilst the first character is being transmitted, no further transfer from the drum into the register can take place. f2.2 non-energised prevents G23 (Fig. 4) opening and f6.2 remains energised. The contents of the memory will be recorded by F9 as read by F3, as indicated by Fig. 8(g) which is the same as Fig. 8(1).

When f2.2 is re-energised, the -first PT pulse which follows opens G23 and f6.1 is energised as shown in 8, Fig. 8. Because M1 is now 1, F3 is at f3.1 and G28 is not opened by the PM pulse coinciding with M1.

Instead it opens for the PM pulse coinciding with M2,v

which is read as 0, F3 going to f3.2. The elements in CH1 are recorded as read by F3, under control of G40 and G41. At time t2, PM, of the M2 element, G28 opens and f7.1 is energised. The elements in CH2 now pass via G16 (Fig. 3) into RL() and are stepped along The record is now asin Fig. 8(11) which diters from (g) in respect ofthe MIZ element only. f7.2 (Fig. 4) is re-energised via G29 for the PM' pulse coinciding with M3. At the same time G5 (Fig. 2) opens, f2.1 is energised and the time scale started. F10 (Fig. 6) causes the contents of R1, which denote the second character, to be transmitted 4to line together with the necessary start and stop elements.

Nothing further occurs until this character is fully transmitted, the recording being made as read. When the time scale is stopped by G7 opening when the necessary 71/2 uniperiods have elapsed, f2.2 being re-energised allows the next PT pulse to open G23 (Fig. 4) and (See 9, Fig. 8,) The fact that f3.2 is energised for M3, and not for Ml-and M2, causes'G28 to open and f7.1 to be energised at a time t3, PM coin- Consequently at c2.3, G53

.ciding `.vt/ithlvil. f6.1, which remains` energised until. `time, causesM1, M2 and M3 to be recorded as 1by means of G38. f7.1 allows the contents of CH3 to .pass to R1 in the manner already described. Since this is the last character, there are no further PM pulses in this section and .f2.1 (Fig. 2) is energised via G8 and G6. The third, and last character, as stored in R1, is now transmitted to line by means of F10. The recordings now as shown in Fig. 8(1').

When the last character has been transmitted, and f2.2 re-energised, f6.1 will again be energised by the'PT pulse (see 10, Fig. S) but now that M1, .M2 and M3 are all 1, G28 cannot open. f6.1 causes these elements to be re-recorded as 1. F6 is returned to f6.2 energised by means of G27, which operates with the last pulse of the section, PL. Element T is recorded as l by means of G32 and the contents of CHl, CH2 and CH3 are recorded by means of G46 and G41 and the recording remains as shown in Fig. 8(1').

After the message has been sent, it is possible to return to the initial state by automatic means but this would entail the use of an auxiliary head and attendant equipment to change the state of element T back to 0. `For convenience it has been assumed that to return to the initial state, the operator restores KRO. When KRO is restored (see 11, Fig. 8), the next PT pulse opens G33 (Fig. 5) and f9.2 is energised causing `a 0 to be recorded for element T. Also the PT pulse opens G23 (Fig. 4) causing f6.1 to be energised as in previous cycles but this time G31 opens also, because T was previously a l and f3.1 will be energised, and, in consequence, f8.1 is energised. Thus in the subsequent PM pulse, a time t3, G26 `is opened and f6.2 re-energised. However, since f6.1 is Vstill energised at t2 of this pulse, a l is recorded Via G38 (Fig. 5) for element M1. For the followingPM pulses, f6.2 will be energised and G39 opens, and not G34, and M2 and M3 are recorded as 0. The recording is now as shown in Fig. 8(1), and is the same as the initial recording. Until a further message is sent from the teleprinter this record will be .recorded by F9 as read, under control of the respective gates and the control equipment will remain in the initial state.

As shown in the diagram, when retransmission is taking place, a new character is not transferred from the drum into R1 until the previous character, including stop elements, has been transmitted. This represents a small wastage of time but this wastage could be removed by modifying the arrangement so that a new character could betransferred during the stop period of the character then being transmitted.

The system has been described for one teleprinter termination and one recording section. However, by means of a multiplex arrangement, such as described in our above mentioned copending applications more than one message could be stored on one track. This has not been described here to avoid unnecessary complication. For such a system Figs. 2, 3 and 6 would be individu-al to the terminating circuits but Figs. 4 and 5 would be common to all message sections on one track. The connections between the individual terminations and the common circuit, e.g. 115.1 and f4.2 would be multipleXed.

As described, a ixed message length has been assumed but simple modifications would make it possible to have a varying length of message. For instance, a special end of message character could be used; detection of Irhis character would be used to cause: the T element to be made l. Similarly, when reading out, detection of the end of message characters would be used to cause T to become 0 again and the recording returned to the initid state.

Further, the system has been described as applied to one track on a drum. A drum may, however, readily accommodate up to 200 tracks side by side, with their reading and recording heads staggered if necessary 11 around the periphery so that not more than, say, 20 must be accommodated side by side axially along the drum. A single clock track on `the drum can then control the operations for recording and reading for the whole 200 tracks so that messages from various destinations may be stored simultaneously (or contemporaneously) on several tracks while messages already stored are being retransmitted from other tracks.

It is, moreover, pointed out that the operations for recording (or reading) and advancing the register, which involve the M1, M2 etc. pulses, are effected `with the one head. That is to say, that the wor head is also utilised for making the identifying transitions from 1 to 0, or for detecting the transitions from to 1, as the case may be, for determining when recording (or reading) may begin.

A further alternative, not at present regarded as a preferred arrangement, is to effect the transfer from register to store element by element instead of character by character (a character being, in the example described, a collection of iive elements). For this, R1 in Fig. 3 would be a simple bi-stable device, which is effectively a 2-position register, and the drum speed would need to be arranged so that the rotation time was less than an elemental period (in the example 20 milliseconds).

Equally to go in `the other direction, each individual store, i.e. between M markings, could be arranged to accommodate more than one character with suitable rearrangement of the controls.

While the principles of the invention have been described above in connection with specific embodiments, and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What we claim is:

1. Equipment for the storage and re-transmission of a plurality of items of intelligence consisting of coded electrical signals, comprising an incoming receiving channel, an outgoing transmitting channel, a record member containing a plurality of recording tracks each including a plurality of electrical signal stores, receiving means for receiving items of intelligence over said incoming channel and applying them successively to predetermined ones of said stores, means associated with said stores for deriving a plurality of control pulses, transferring means for applying predetermined ones of said pulses successively to different ones of said stores as to set up thereby distributor signal marks in said stores to mark the order of the successive predetermined use of said stores as repositories of said intelligence, and means for successively transmitting over said outgoing line in the order as recorded stored items of intelligence previously recorded in said stores.

2. Equipment as claimed in claim 1 wherein said receiving means include means for the reception of constant total permutation code characters of n elements, one character per store, and which comprises a temporary store arranged to store a single character, means for completely receiving the elements of each character on receipt in the said temporary store, and means for completely transferring a temporarily stored character into the next one ofsaid plurality of stores to be used.

3. Equipment as claimed in claim l wherein said receiving means includes means for the transmission of constant total permutation code characters of n elements, stored one character per store, and which comprises a temporary store arranged to store a single character, means for completely transferring the elements of a character to be transmitted to said temporary store under control of said marking means, and means to transfer said temporarily stored character to a permutation code signal transmitter.

v4. Equipment as claimed in claim 2 and in which said temporary store comprises a pattern movement register of known type.

5. Equipment for the reception, storage and subsequent re-transmission of constant ftotal permutation code characters comprising a start element, n variable elements, and a stop element, which comprises an incoming line, an outgoing line, a track on a magnetic drum constituting a plurality of storage sections, recording and reading means for sai-d track, a temporary store comprising a pattern movement register, means for receiving from said incoming line all the variable elements of a complete character in said register, distributing means for applying a mark to said track for indicating the next section thereof to be used for storage, means for detecting such mark, means under control of said detecting means and the stop element of the character in said temporary store to cause the transfer of the contents of said temporary store into said marked storage section, means to cancel a detected mark on transfer and to insert a new mark at the end of transfer at the beginning of the next track storage section; means to initiate transmission of stored characters from said storage sections, including means to detect an identifying mark in the storage section containing the iirst character stored, means to transfer to said temporary store the rst character stored in a storage section, means to transmit with stop and start elements a character stored in said temporary store to said outgoing line, means to transfer thereafterin turn to said temporary store character stored in subsequent sections of said track, and means to transfer said identifying mark from storage section to storage section as each storage section on said track is emptied.

6. Equipment for the sequential storage of a plurality of items of intelligence consisting of coded electrical signals, comprising a record member containing a plurality of reconding tracks each including a plurality of electrical signal stores, means for applying a distributor signal mark to a rst store which is in a condition to receive and store a first item of intelligence, distributor mark transferring means responsive to said first store being taken into use for cancelling the distributor mark signal from said first store and applying a distributor mark signal to a second store, detecting means for sequentially examining said stores for the presence of a distributor signal mark and means responsive to said deftecting means for successively directing said iirst and a second item of intelligence, respectively to said rst and second stores in the order named.

7. Equipment for the storage and subsequent retransmission of a plurality of items of intelligence consisting of coded electrical signals, comprising a record member containing a plurality of recording tracks each including a plurality of electrical signal stores, means for recording said items of intelligence successively in said stores, means for applying a distributor signal mark to a first store containing the rst item of intelligence to be transmitted, distributor mark transferring means responsive to said rst store being emptied for cancelling the distributor mark signal from said iirst store and applying a distributor mark signal to the store in which said second item of intelligence is stored, detecting means for sequentially examining said stores for the presence of a distributor signal mark, and means responsive to said detecting means for successively extracting said rst and second items of intelligence yfrom said first and second stores, respectively, in the order named.

References Cited in the tile of this patent UNITED STATES PATENTS Hamilton a Nov. 13, 1956 

